In order for soldiers and the like to maintain the combat skills it is important that they regularly engage in training exercises. However, such training can also be time consuming and expensive. For example, when training for tank combat, there is considerable cost in fuel, targets, ammunition and related materials. Additionally, the soldier's time and the amount of time which they occupy a training facility are important, as there may be a large number of soldiers who need to be trained on limited facilities. Thus, it is important that targets remain in an operational state, and that if a target is damaged or otherwise becomes non-operational the target can be quickly returned to an operational state. Preventing targets from becoming non-operational and allowing them to be quickly repaired and placed back into operation is advantageous as it eliminates downtime at the training facility and reduces the operational costs of the target system. In some cases, time limits for repair and placing a target back to an operational state is part of a required performance specification for a target system.
Large targets such as tank targets may include a trolley which moves on rails and a large target mounted to the trolley. These trolleys may weigh several thousand pounds, as they carry a large target overhead, and must resist tipping over in wind storms and when moving along a track. These trolleys may travel at speeds of up to 40 miles per hour or faster to simulate a tank moving at full speed. While such tank target systems usually include brakes, there are times when the brakes either fail or are insufficient to stop the trolley prior to the end of the track.
As the heavy trolley reaches the end of the tracks, it is important that it be stopped. In the case of a brake failure or too little stopping distance, the trolley can overrun or jump off the tracks. If the trolley jumps the tracks, a heavy lifting rig must be brought in and the trolley must be placed back on the tracks. The trolley may also be damaged and must be repaired. In either case, a significant delay is possible.
In some cases, to prevent a runaway trolley, sand has been placed around the end tracks to decelerate the trolley. While this may prevent the trolley from travelling well off the end of the tracks or damage to the trolley if it hits an abutment at the end of the tracks, the sand seems to get drawn in the wheels, etc. of the trolley and can delay redeployment of the trolley. Thus, once the trolley stops in the sand, a crew should go in and clean the sand out of the trolley. Even if cleaned, some sand may remain and further damage the trolley during further exercises. Such cleaning wastes both time and man-power.
Thus there is a need for an emergency stopping mechanism for a trolley that avoids the contamination of the trolley, while keeping the trolley from running off the end of the tracks.